Allred Rachel P, Cappellini Colleen H, Jones Theresa A
Department of Psychology.
Institute for Neuroscience.
Behav Neurosci. 2010 Feb;124(1):124-132. doi: 10.1037/a0018457.
Following stroke-like lesions to the sensorimotor cortex in rats, experience with the ipsi-to-lesion (ipsilesional), "nonparetic", forelimb worsens deficits in the contralesional, "paretic", forelimb. We tested whether the maladaptive effects of experience with the nonparetic limb are mediated through callosal connections and the contralesional sensorimotor cortex. Adult male rats with proficiency in skilled reaching with their dominant (for reaching) forelimb received ischemic bilateral sensorimotor cortex lesions, or unilateral lesions, with or without callosal transections. After assessing dominant forelimb function (the paretic forelimb in rats with unilateral lesions), animals were trained with their nonparetic/nondominant forelimb or underwent control procedures for 15 days. Animals were then tested with their paretic/dominant forelimb. In animals with unilateral lesions only, nonparetic forelimb training worsened subsequent performance with the paretic forelimb, as found previously. This effect was not found in animals with both callosal transections and unilateral lesions. After bilateral lesions, training the nondominant limb did not worsen function of the dominant limb compared with controls. Thus, the maladaptive effects of training the nonparetic limb on paretic forelimb function depend upon the contralesional cortex and transcallosal projections. This suggests that this experience-dependent disruption of functional recovery is mediated through interhemispheric connections of the sensorimotor cortex.
在大鼠感觉运动皮层出现类中风损伤后，使用同侧（即损伤侧）“非瘫痪”前肢的经验会使对侧“瘫痪”前肢的功能缺陷恶化。我们测试了非瘫痪肢体经验的适应不良效应是否通过胼胝体连接和对侧感觉运动皮层介导。成年雄性大鼠，其优势（用于抓握）前肢熟练掌握抓握技能，接受双侧感觉运动皮层缺血性损伤，或单侧损伤，伴或不伴胼胝体横切。在评估优势前肢功能（单侧损伤大鼠的瘫痪前肢）后，动物用其非瘫痪/非优势前肢进行训练或接受15天的对照程序。然后用其瘫痪/优势前肢对动物进行测试。仅在单侧损伤的动物中，如先前发现的那样，非瘫痪前肢训练会使随后瘫痪前肢的表现恶化。在胼胝体横切且单侧损伤的动物中未发现这种效应。双侧损伤后，与对照组相比，训练非优势肢体并未使优势肢体的功能恶化。因此，训练非瘫痪肢体对瘫痪前肢功能的适应不良效应取决于对侧皮层和胼胝体投射。这表明这种依赖经验的功能恢复破坏是通过感觉运动皮层的半球间连接介导的。
